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Physico-chemical parameter: the visible absorption spectrum of OBrO investigated by Fourier transform spectroscopy

By the utilization of a new laboratory method to synthesize OBrO employing an electric discharge, the visible absorption spectrum of gaseous OBrO has been investigated. Absorption spectra of OBrO have been recorded at 298 K, using a continuous-scan Fourier transform spectrometer at a spectral resolution of 0.8 cm-1. A detailed vibrational and rotational analysis of the observed transitions has been carried out. The FTS measurements provide experimental evidence that the visible absorption spectrum of OBrO results from the electronic transition C(2A2)-X(2B1). Vibrational constants have been determined for the C(2A2) state (1 = 648.3 ± 1.9cm-1 and 2 = 212.8 ± 1.2cm-1) and for the X(2B1) state (1 = 804.1 ± 0.8 cm-1 and 2 = 312.2 ± 0.5cm-1). The vibrational bands (1,0,0), (2,0,0), and (1,1,0) show rotational structure, whereas the other observed bands are unstructured because of strong pre-dissociation. Rotational constants have been determined experimentally for the upper electronic state C(2A2). By modelling the band contours, pre-dissociation lifetimes have been estimated. Further, an estimate for the absorption cross-section of OBrO has been made by assessing the bromine budget within the gas mixture, and atmospheric lifetimes of OBrO have been calculated using a photochemical model.

Citation: Fleischmann, O.C.; Burrows, J.P.; Orphal, J. The visible absorption spectrum of OBrO investigated by Fourier transform spectroscopy, Journal of Physical Chemistry A, 2005; ASAP Article; doi: 10.1021/jp044911x

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Institute of Environmental Physics and Remote Sensing IUP/IFE, UNIVERSITAET BREMEN
Postfach 330440
28334 BREMEN
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